Hunters, man. We got the jumps! Don't actually know if this is possible with other classes, but highly doubt it. Engineers might be able to do it.
Thanks to disengage being usable outside of combat, I've found that it is possible for us to get up to the forbidden lounge in the Brawlpub and get into the arena (for all of two seconds). Considered putting this in the exploits section, but It currently seems to be more on the [Useless] side. If somebody finds a way to cheese a fight or two, they can go ahead and put that in that section.
The Glyph of Disengage and a Vrykul Drinking Horn (or other growth effect) are all that's needed. About the Glyph, it increases the horizontal distance that your disengage takes you. To accomplish this, it sends your character in a higher arc. This extra boost in height is useful for reaching those places that a normal jump just doesn't quite reach.
And no, nothing outside of the normally accessible area is solid. Fell into the void numerous times testing the tunnels and the tram carts.
Pardon the terrible video. It's my first one ever, but any quality issues are *not* the fault of Movie Maker. :P